During the next grant period our aims are as follows: 1) Complete the characterization and quantitative analysis of velocity-sensitive mechano-receptor neurons of the deep layers of the superior colliculus; 2) Extend studies on the use of (H3) adenosine for autoradiographic analysis of axonal transport in the visual system; 3) Continue studies of anterograde transport of tritiated amino acids from the deep collicular layers; 4) Study of the tectospinal and spinotectal projection using retrograde transport of horseradish peroxidase; 5) Complete construction of a computer-controlled visual stimulator for study of velocity-sensitive visual neurons. All the above experiments are to be performed primarily on cats.